Offloading Difficult Wounds and Conditions in the Diabetic Patient

- Pressure reduction is the cornerstone to preventing and healing foot ulcers in people with neuropathy. Total contact casting (TCC) is the most commonly used and extensively researched method to reduce plantar pressure.
- However, TCC is not the ideal treatment for all patients with wounds and rarely used for prevention.
- Fortunately, today clinicians may choose from many different offloading devices. Because their optimal use and effectiveness often hinges upon comfort and ease of use, a careful review of all options and their advantages and disadvantages can, literally, save a limb.
Issue Number:
1
author:
Robert J. Snyder, DPM, FACFAS, CWS, and Karen K. Lanier, CPed

Lower extremity wounds represent significant medical and financial challenges to the healthcare system. This is especially the case in the diabetic population where neuropathy, often associated with vascular disease, can lead to ulceration, immobility, infection, and gangrene. One study places the average cost of healing a single diabetic ulcer at approximately $36,000,1 leading to direct costs of $600 million dollars annually.2 Limitations on mobility caused by foot ulcers have a negative impact on social, psychological, physical, and economic domains.3 Charcot arthropathy can create additional complications; all of these sequelae can lead to major limb amputation.1 Early recognition and prompt management of these foot ulcers can facilitate healing.4 Additional data suggest that meticulous, scientifically based wound care and patient education strategies can reduce lower extremity amputation rates by reducing the frequency and severity of foot ulcers.5
In response to the high costs of managing chronic wounds, systems of comprehensive outpatient care have been established and represent an interdisciplinary and collaborative approach to wound management. The goals of wound care protocols are to treat underlying conditions that cause wounds, facilitate the wound healing process, and minimize skin breakdown and wound recurrence.6 The scope of potential interventions includes debridement, infection control, offloading, protective and active dressings, revascularization, proper nutrition, and patient education.7 Offloading is important for reducing foot pressure points8 and for prevention,9 as well as for healing.10
The following article discusses offloading difficult wounds and Charcot foot at various stages of treatment and prevention. The pedorthic management of foot amputations also will be discussed.

The Neuropathic Ulcer
The main cause of foot ulceration is neuropathy (see Figure 1).11 This leads to prolonged and excessive pressures that cause tissue breakdown. Using footwear as a means of healing open wounds is rarely desirable.12 Currently, total contact casting (TCC) (see Figure 2) represents the gold standard for the treatment of forefoot and midfoot (Wagner grade 1-2) diabetic and neuropathic ulcerations; however, reduction of heel pressures with this device remains controversial. Myerson et al13 estimate that 6 weeks of treatment in a total contact cast costs the same as a single day of inpatient treatment. Specialized casting protects the foot from trauma, immobilizing skin edges and reducing edema. It decreases pressure over the ulcer by redistributing the weightbearing load over a greater plantar surface area.
Molding the bottom of the cast to the bottom of the foot causes the entire sole to participate in the force distribution, resulting in lower pressures.14 In 1985, Birke et al15 reported 75% to 84% reduction of peak pressure at the first and third metatarsal heads, respectively, when subjects walked in a cast. Many other studies have supported the successful rationale for TCC use. For example, Sinacore et al16 noted healing in 82% of 33 ulcers after an average of 44 days in a total contact cast. Myerson et al13 observed healing in 64 out of 71 (90%) ulcers at a mean of 5.5 weeks. Hanft et al17 performed a 10-year retrospective study utilizing total contact casts on more than 1,000 patients. The research demonstrated a healing rate of 91% within 13 weeks with an average closure time of 4.36 weeks (± 1.31 weeks). It was concluded that the total contact cast was an effective, low-risk, and inexpensive treatment for plantar diabetic foot ulcers.
Total contact casting has several disadvantages, including joint stiffness, muscle atrophy, the possibility of new ulcerations and skin breakdown, labor-intensive application, and possible laceration of the patient during cast removal. Contact dermatitis and fungal infection also may occur and should be treated with appropriate topical medications and temporary abstinence of casting. Patient compliance due to the absence of pain is also an issue. Although TCC is an ambulatory procedure, the patient is required to limit ambulation to one-third normal. This often requires counseling and close follow-up while the cast is in place. Vascularity must be carefully evaluated before cast application. Lavery et al18 discovered that TCC causes postural instability in the ambulating patient as compared to a tennis shoe or removable cast walker; therefore, consideration for the well being and safety of the patient must be strongly considered before recommending the device.
Alternatives to TCC may include the following (examples of device alternatives are pictured in Figure 2):
- Nonweight bearing
- Standard below-knee casts
- Charcot Restraint Orthotic Walkers (CROW)/total contact brace
- Prefabricated walker
- The DH walker (Centec Orthopaedics, Camarillo, Calif.)
- The Integrated Prosthetic and Orthotic system (IPOS, Niagara Falls, NY)
- Orthowedge (Darco International, Huntington, WV)
- Healing sandal
- Reverse IPOS heel relief shoe system
- L?Nard Splint/MultiBoot? (AliMed Inc., Dedham, Mass.)
- Standard ankle/foot orthoses (AFO)
- Patella tendon bearing brace (PTBB)
- Prefabricated pneumatic walking brace (PPWB)
- MABAL shoe/Scotch boot
- Additional considerations.
Nonweight bearing. This can be accomplished with bed rest, wheelchair, walkers, crutches, and similar strategies and appliances. However, wheelchairs are cumbersome and may not permit mobility in the patient’s home. Crutches and walkers may actually increase pressure to the contralateral limb.19 Diabetics may lack the upper body strength, cardiovascular reserves, or motivation to consistently use these modalities.20 Noncompliance is a significant issue with these devices.
Standard below-knee casts. Several studies support similar efficacy between the total contact cast and the standard cast.21 Plaster or fiberglass tape appears to be equally efficacious.22 However, patients with neuropathy run the risk of injury from the edge of the cast or from material working its way into the open toe design; therefore, the closed toe design of the TCC appears to be superior.
Charcot Restraint Orthotic Walker (CROW). This device (see Figure 2) is also known as a ?clamshell? or bivalved AFO (BAFO). It is composed of a polypropylene material, lined with plastizote, incorporates a total contact custom molded orthotic, and utilizes a rocker bottom sole. The CROW is the treatment of choice for many clinicians during the quiescent second and third Eichenholtz stages of the neuropathic process where joint stability and alignment must be maintained.23
The advantages of the CROW include:
- ability to inspect and treat the ulcer as needed by removing the appliance
- minimal joint stiffness and atrophy
- ability to utilize growth factors and other topical medications and dressings
- ability to control edema
- allows for ambulation
- provides patient satisfaction.
Among the CROW’s disadvantages:
- removability – the patient can remove and ambulate without protection
- cumbersome relative to size and weight and may not be appropriate for frail individuals, patients with motor difficulties, or morbidly obese patients
- likelihood of skin irritation and breakdown – should be worn over a support stocking or knee-high cotton hose
- requires frequent adjustments to accommodate for reductions in edema.
Prefabricated walker. Originally designed for the treatment of fractures and sprains, a prefabricated walker may be useful in the offloading treatment of diabetic foot ulcers.24 Hanft et al25 performed a retrospective study of more than 300 patients with plantar diabetic foot ulcers and demonstrated a healing rate of 85% within 13 weeks with an average time to closure of 5.51 weeks (± 1.02 weeks). In another study, the prefabricated walker has been shown to reduce foot pressures by as much as 56% to 58% and one specific model by 63% to 70%.26 Diabetic ulcerations must be protectively padded and closely monitored. Prefabricated walkers are of additional benefit because they can be removed to inspect and treat ulcerations as needed and can be reused in cases of recidivism. Other advantages appear similar to that of the CROW boot. The caveat lies in the patient?s potential for noncompliance (see Figure 2).
The DH walker. This device is similar to the commercial walking brace; however, the floor of the device contains prongs made of polyethylene that can be removed to effectively accommodate an ulceration or deformity. These removable prongs (hexagons) are also available in an offloading shoe design. Fleischli et al26 postulated that the DH pressure relief walker reduced plantar pressures by 79% to 80% and appeared to be as efficacious as the total contact cast in reducing plantar pressures in the great toe. In this study, the device appeared to be superior to the TCC in reducing plantar pressures for ulcerations under the first metatarsal (see Figure 2).
The Integrated Prosthetic and Orthotic System (IPOS). The IPOS model is indicated for treatment of forefoot ulcers. This “half shoe” is designed with 10 degrees of dorsiflexion and a heel that is elevated 4 cm to prohibit forefoot contact with the ground. The device is inexpensive and stimulates a high rate of patient compliance. Its main disadvantage appears to be the patient’s difficulty with balance. The modality requires dorsiflexion, which is often compromised in the diabetic population. One study revealed that patients wearing “half-shoes” healed faster and more efficiently and had fewer serious infections when compared to patients receiving similar therapy who did not wear the shoe (see Figure 2).23
Orthowedge. This device is similar to the IPOS design except the sole extends to the toes. Again, the patient’s ability to perform adequate dorsiflexion is at issue. One study showed plantar pressure reduction of 64% to 66% utilizing this modality, yet the device was less effective than the TCC or DH walker (see Figure 2).19
Healing sandal. This device is constructed with a dual density total contact orthotic made of plastizote. The orthotic contains a cutout under the ulcerated area, and the edges are skived (beveled) to minimize stress. The insole is then placed in a Darco-type postsurgical shoe. Hanft et al29 performed a study of more than 500 patients with plantar diabetic foot ulcerations and demonstrated a healing rate of 74% within 13 weeks with an average time to closure of 7.11 weeks (± 2.35 weeks). Advantages include a lightweight design that is more aesthetically pleasing than the TCC or CROW boot. The main disadvantage is poor control of foot motion, which may lead to increasing stress at the lesion site (see Figure 2).
Reverse IPOS heel relief shoe. This appliance offloads at the heel with a shoe design that is open at the back and angled in 10 degrees of plantar flexion. Although lightweight and relatively inexpensive, this device may create gait instability and difficulty with balance (see Figure 2).
L’Nard splint/multiboot. This device enables pressure-free suspension without foot irritation and features a swing-out antirotation bar and height-adjustable footplate to keep the bedding from pressing on the toes and foot (see Figure 2).
Ankle foot orthoses (AFO). This device is constructed of molded thermoplastic material and represents a rigid ankle design. Used with or without a dorsal foot strap, it is indicated for a multitude of conditions including drop foot, rotational control and weight reduction of a residual foot, and for medial to lateral stability. An AFO can be made in a rigid or articulating design (see Figures 3a and 3b).
Patella tendon bearing brace (PTB). This custom offloading brace transfers weight from the foot to the patella and properly positions the foot for ambulation. The modality also increases rotational control of the lower extremity; thus, reducing pressure to prevent and treat distal ulcerations.30 Its custom-molded polypropylene copolymer is designed as a “clamshell” AFO and fits footwear that has additional depth. The patella tendon bearing brace has decreased the rear foot mean forces by at least 32%.31 Disadvantages include size, cost, and aesthetics. The device is also confining, bulky, creates additional pressure on the patella, and may be a factor in noncompliance because it is removable (see Figure 2).
Prefabricated pneumatic walking brace (PPWB). Using inflatable and adjustable air cells, this device functions as a removable cast. One study revealed that the PPWB was superior to the TCC in decreasing plantar pressures.32 Benefits include reasonable cost and the ability to inspect a wound. One disadvantage is the potential for patient noncompliance.MABAL shoe/Scotch boot. This is a removable fiberglass combination of a cast and a shoe (the initials represent an acronym for its inventors and place of origin). Hissink et al33 studied patients with a total of 23 ulcerations and discovered that 21 healed with a mean healing time of 34 days (7 to 75 days). It was concluded that the MABAL shoe provided healing of neuropathic diabetic foot ulcers comparable to existing methods of treatment. The main advantages of this modality include mobilization of the ankle, removability, and less time-consuming application when compared to the TCC. An additional modification formulated by the authors includes the attachment of Velcro? between the bottom of the shoe and the sole, allowing for the removal of the sole during sleeping, if desired (see Figure 2).
Additional considerations.
Felt and foam total contact padding. This technique creates an aperture (or opening) in a piece of felt and/or foam to accommodate an ulcer. The material is subsequently applied directly to the full length of the plantar aspect of the foot. This pressure-relieving strategy is easy to apply, usually causes no secondary lesions, encourages patient compliance, and is cost effective. Unfortunately, much of the evidence regarding efficacy of this modality is anecdotal.34
Bledsoe conformer diabetic boot (Bledsoe Brace Systems, Medical Technology Inc, Grand Prairie, Tex.). This device was specifically designed for diabetic patients with problematic ulcerations. The boot features a fully enclosed thick foam cocoon attached to an auto-molding innersole that embeds into a specially designed premolded midsole insert in aluminum shelled walking boot. Pollo et al35 conducted a study on 10 normal subjects with no prior history of foot or ankle problems and determined that the Bledsoe conformer functioned as well or even better than a total contact cast with the added convenience of allowing removal of the boot for wound examination. However, this study represents a small sampling and additional investigation is underway to expand clinical data with regard to healing time and pressure differences.
Once the wound is healed, maintaining closure is imperative. Recurring ulceration is usually due to noncompliance with prescription shoe wear. A lack of protective shoe gear is the most common cause of ulcer recurrence.36 A study undertaken by Helm et al37 revealed a recurrence rate of 19.4% out of 102 patients. Myerson et al13 postulated a recurrence rate of 31% out of 71 patients. These findings were supported by a Centers for Disease Control study that determined that diabetics with proper shoe protection had only a 20% recurrence, while those without had an 80% recurrence.36
Preventing recidivism. The following modalities can be utilized to prevent recidivism.
Custom molded shoes. Prescription shoes accommodate, stabilize, and support deformities and limit inappropriate motion of joints. These measures can decrease inflammation and pain and reduce pressure on the foot.32 Molded shoes are individually constructed over a modified positive model of the individual’s foot. The molded shoe should be deep enough to accommodate a removable insole. The federal government, through the Medicare “Therapeutic Shoe Bill,” recognizes the benefit of special shoes and insoles made for diabetic patients.40
Depth shoes. These shoes provide additional vertical depth of 3/16 to 1/2 inch. Wide shank depth shoes give additional width in the girth (instep).
Depth wide shank shoes. This shoe is 1/4-inch deeper than regular depth shoes and will accommodate up to a 1/2-inch inlay.
Moldable shoes. The entire lining of this shoe is constructed of 1/8-inch foam and is covered with a seamless fabric. This shoe is moldable (when heated) and can accommodate many different deformities by using a “ball and ring” device.
Full contact orthoses/total contact insert (TCI). Special insoles reduce foot pressures by as much as 50%.40 These devices are molded over a positive model or directly to the patient?s foot with appropriate posting. This modality is made of material that may accommodate the deformity, and/or alters lower extremity biomechanics. A full-contact orthosis requires shoes of sufficient depth.
Steel shanks and extended shanks. Steel bars are used with the rocker sole to reduce metatarsophalangeal extension or provide better biomechanics for the transmetatarsal amputee.SACH heel and other heel modifications. The insertion of a SACH heel to the rear midsole of a patient’s shoe acts as an extrinsic shock absorber. This device is constructed of a high-density material with give and is inserted to prevent wear while absorbing shock and immediately rebounding for the next heel strike. SACH heels often are used in conjunction with short leg braces and can replace some of the lost rotational movement of the limb on the foot when such torque is lost due to fusion or trauma.41 This device also can stabilize the foot after partial calcanectomy. Wedging is frequently used for stabilizing a flexible deformity in a corrected position or in accommodating a fixed deformity. A medial wedge is indicated in extreme pronation, and a lateral wedge can be used for ankle instability or a varus heel deformity. Wedges can be placed between the upper and the sole or directly on the bottom of sole. Heel and sole flaring often are used for support. This type of modification provides medial lateral stability to the foot on the side that it is applied. Flaring is often united with wedging for maximal effect (see Figure 4).
Rocker bottoms. Rocker-sole shoes are one of the most commonly prescribed shoe modifications.42,43 They represent exterior additions to the outsole that taper off at the distal tip and may taper off to the posterior edge of the heel, creating changes in biomechanical function.
In general, rocker soles are custom made for each patient; six basic types of rocker soles can be identified based on the variation of position and the degree of the rocker angle (see Figure 5).
1. Mild rocker sole – The most widely used and most basic of the rocker soles has a mild angle at both the heel and the toe. This type of rocker sole can relieve metatarsal pressure and may assist gait by increasing propulsion and reducing energy expended when walking. It is appropriate for the foot that is not at risk and typically found on athletic walking shoes.
2. Heel-to-toe rocker sole – Shaped with a more severe angle at both the heel and the toe, the heel-to-toe rocker is extended to provide greater propulsion at toe off. This causes a decrease in heel strike and reduces the need for full range of ankle motion. The modality is appropriate for a fixed claw toe, rigid hammertoe, midfoot amputation, calcaneal ulcers, or for the patient who has undergone triple arthrodesis.
3. Toe-only rocker sole – The purpose of a toe-only rocker sole is to increase weight bearing behind the metatarsal heads, provide stability at midstance, and reduce the need for toe dorsiflexion. It is useful for hallux rigidus, hammertoes, and metatarsal ulcers associated with diabetes.
4. Severe angle rocker sole – This type of sole also has a rocker angle only at the toe; however, the angle is much more severe than that found on the toe-only rocker sole. This device eliminates the weight-bearing forces at the metatarsal heads and anterior to them and is most often used for extreme relief of diabetic ulcers at the metatarsal heads.
5. Negative heel rocker sole – Shaped with a rocker angle at the toe and a negative heel, this type of rocker sole results in the patient’s heel being at the same height or lower than the ball of the foot when the patient is standing. The negative heel rocker sole accommodates a foot that is fixed in dorsiflexion and/or relieves forefoot pressure by shifting it to the hind foot and midfoot. The negative heel rocker sole should be used with caution because the patient’s inability to attain the appropriate ankle dorsiflexion may cause discomfort and ultimately increase pressure on the problem area.
6. Double rocker sole – This is a mild rocker sole with a section removed in the midfoot area; thereby, giving the appearance of two rocker soles – one at the hind foot and one at the forefoot (two areas of midstance). Because the thinnest area of the double rocker sole is at the midfoot, it is used to relieve a specific midfoot problem area, such as the Charcot foot deformity associated with diabetes.

Charcot Foot (Osteoarthropathy)
The etiology of Charcot foot (see Figure 6) is multifactorial and based on neuropathy and metabolic processes.44 Neuropathic arthropathy may be defined as a relatively painless, progressive, and degenerative condition of single and multiple joints caused by underlying neurological deficits.45 Additional neurovascular theory postulates that increased peripheral blood flow due to autonomic neuropathy leads to a hyperemic bone resorption.46 Other predisposing factors may include renal transplantation, immunosuppressive therapy, impaired cartilage growth, and nonenzymatic glycosolation.45 Sadly, these deformities can result in major limb amputation.47
Eichenholtz48 described the stages of bone and joint destruction followed by fracture healing and remodeling. This temporal classification is based on the characteristic clinical and radiographic changes that occur with neuropathic joint destruction and fracture over time; progression occurs from the acute phase (dissolution) through the healing phase (coalescence) to the resolution phase. The resulting foot deformities cause difficulty with shoe fit and significantly increase the propensity toward ulceration in high-pressure areas.49 Almost all patients with these deformities will ultimately require specialized footwear with custom total-contact inserts or custom bracing. Surgery for these conditions is predicated on the goal that restoration of stability and alignment of the foot and ankle will make appropriate shoeing and bracing possible.50 Foot ulcers in association with significant neuropathic deformity are usually treated with many modalities, ranging from total-contact casts, CROW boots, AFO, PTB devices, and removable prefabricated walking braces to custom molded insoles, bracing, and shoes. The type of appliance used is predicated on the Eichenholtz stage of development.
Eichenholtz stages.
Stage I (Dissolution). Radiologically, regional bone demineralization with periarticular fragmentation and joint disarticulation is present. Clinically, acute inflammation, swelling, erythema, and heat are evident. This early stage is easily mistaken for infection or thrombophlebitis.51 Treatment is nonweight-bearing and usually consists of a total contact cast, BAFO, CROW boot, or a removable prefabricated walking brace. One study of 34 feet revealed that treatment averaged 8.4 months. However, follow-up could continue for 35 months or more.52 As treatment progresses, care must be taken to gradually wean the patient from nonweight-bearing to partial and then full weight-bearing along with the help of assistive devices; these include appropriate and professionally guided use of crutches, walkers, or canes.53
Stage II (Coalescence). Radiologically, absorption of bone debris in the soft tissues is evident, along with organization and early healing of fracture fragments and periosteal new bone formation. Clinically, a decrease in inflammation with less fluctuance can be noted as well as increased stability of fracture segments. A study of 43 feet in this classification30 revealed that immobilization lasted an average of 6.4 months in 34 of the feet and follow-up averaged 16.4 months.
Stage III (Resolution). Radiologically, a smoothing of large bone fragment edges is present, along with sclerosis and bony/fibrous ankylosis. Clinically, permanent enlargement of the foot and ankle, fixed deformity, minimal swelling, and normalization of temperature are evident. A study of 60 feet in this category30 required follow-up for 22.1 months. Treatment consisted of custom-molded shoes and insoles unless ulceration dictated otherwise. No immobilization was required in this group because of the healed nature of the process. Anderson et al21 recommends an extra-depth shoe coupled with a cushioned insert attached to a double-upright calf-lacing brace with a fixed ankle joint and rigid rocker sole. The shoe may need a wide shank or a more rigid rocker if the midfoot or hindfoot areas are involved. The patient also should be fitted with knee-high compression hose. An AFO or CROW can be used as an alternative.

Pedorthic Management of Amputations of the Foot
Partial amputations of the foot are becoming more frequent when compared with transtibial or transfemoral amputations because retained length results in better function and lower energy expenditure.54,55 The goal of surgery is to achieve the most distal level of amputation that will heal. These procedures should result in a stable shoeable or braceable residual limb that allows for maximum rehabilitation.56 The prosthetist should strive to provide a comfortable, safe, stable, and supportive device that is easy to use and adjust.57,30 Function of the amputated part should be stable enough so as not to cause breakdown of the contralateral limb.
Table 1 represents the most common foot amputations and recommendations for accommodation, shoeing, and bracing.

Conclusion
Lower extremity wounds in the diabetic population represent a challenge to the clinician. Treatment is multifocal and includes debridement, infection control, offloading, the use of protective and active dressings, revascularization, and patient education. Offloading is imperative if foot pressures are to be reduced, healing is to progress, and ulcer prevention is to be a realistic goal.
The literature supports the premise that the total contact cast represents the “gold standard” for the treatment of forefoot and midfoot ulcers as well as Eichenholtz classification 1 and 2 Charcot foot disease. The DH walker (pressure relief walker) also achieves significant reduction of plantar pressures at sites of neuropathic ulceration.20 Alternatives to care include standard below-knee casts, CROW boots, and walking braces. Additional modalities include IPOS shoes, pneumatic walking braces, healing sandals, PTB, AFO, MABAL shoes, and L’Nard splints.
Using footwear as a means of attempting to heal open wounds is rarely desirable. However, once healing has occurred, utilizing shoe gear, insoles, and shoe modifications to maintain closure is imperative. This is also true of Charcot foot and amputations of the foot and ankle.
This written and pictorial compendium of modalities and algorithm of care was compiled to aid the clinician in choosing appropriate devices for individual conditions and to update knowledge of available modalities and resources. Constant technological improvements require clinicians to be diligent in seeking additional information on improvements and enhancements when prescribing offloading devices. – OWM
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